The invention relates to three-dimensional moldable articles having interstitials therein, and a process and apparatus for producing such articles.
A wide variety of motionless or static mixer designs are known in the art. Static mixers mix one or more fluids, (gases, liquids, powders, etc.) in a flow stream without the need for external energy input such as occurs with rotating impellers, agitation, etc. One of the most effective static mixers comprises a multi-stage labyrinth of elongate mixing elements forming a lattice structure of intersecting webs and slots. Such a static mixer forms a conduit having intersecting channels which transversely split, axially rotate and recombine one or more component fluid streams into smaller and smaller streams. As the component streams become smaller, the outlet product from the static mixer becomes more homogenous.
A static mixer may have multiple stages. A stage combines component streams flowing in a first direction transverse to the axis of the static mixer, then divides the flow in a second direction occurring transverse to the axial flow direction. U.S. Pat. No. 4,062,524, iss. Dec. 13, 1977 to Brauner et al., and U.S. Pat. No. 4,220,416, iss. Sep. 2, 1980 to Brauner et al., disclose exemplary static mixers.
While the lattice type of static mixer has been generally preferred in the industry, it is difficult to construct. Typically, an assembly of individual bars forming a single stage is sand cast. This process is expensive, as each stage is individually cast and a new mold is required to cast each stage. Additional expense occurs when the stages must be joined, in sequence, in the axial direction as disclosed in U.S. Pat. No. 5,435,061, iss. Jul. 25, 1995 to Lantz. Thus, producing a preferred type of static mixer is a time consuming and expensive process.
Alternatively, static mixers have been made from stamped steel plates. The plates have wing portions extending from bending lines and are alternately bent in staggered relationship. The parts thus formed are then assembled into three-dimensional grids having central strip portions and wing portions which provide fluid passages. Static mixers made according to such processes are illustrated in U.S. Pat. Nos. 5,378,063, iss. Jan. 3, 1995 to Tsukada and 5,522,661, iss. Jun. 4, 1996 to Tsukada.
Attempts have been made in the art to injection mold static mixers. However, the injection molded static mixers suffered from simpler designs which do not combine multiple fluid streams as effectively as a lattice type static mixer. One such static mixer is disclosed as an extrusion in U.S. Pat. No. 5,891,487, iss. Apr. 6, 1999 to Parise.
The art relating to injection molding does not disclose a way to make three-dimensional articles comprised of elongate elements, such as static mixer blades, and having interstitials therethrough. For example, U.S. Pat. No. 4,218,038, iss. Aug. 19, 1980 to Garneau, Sr. discloses a mold for making hair combs. However, such a comb is generally planar. Garneau, Sr. does not suggest a way to mold nonplanar articles.
Accordingly, there is a need in the art for a way to injection mold three-dimensional articles comprised of elongate elements and having interstitials therethrough. Further, there is a need in the art for a way to inexpensively produce static mixers, heat exchangers, and other articles having elongate elements and interstitials. Finally, there is a need in the art to produce static mixers having more than one stage in a single manufacturing step.
The invention comprises a process for producing three-dimensional articles having interstitials therein. The process comprises the steps of providing at least two complementary mold segments. The mold segments are juxtaposable to circumscribe an enclosed cavity. The cavity has an axial direction and radial direction perpendicular thereto. Each mold segment has a plurality of members extending into the cavity, and defining an angle relative to said axial direction. The members are juxtaposed to enclose a cavity therebetween. A flowable solidifiable material is disposed in the cavity. The material is allowed to solidify. Each said mold segment is separated from the solidified material, in a direction parallel to the members of that mold segment.
All documents cited are, in relevant part, incorporated herein by reference. The citation of any document is not to be construed as an admission that it is prior art with respect to the present invention.